Fig 1.
Shoot and root fresh and dry weights, shoot and root lengths of two cultivars of cauliflower (Brassica oleracea L.) plants foliarly treated with thiamin (50 and 100 mM) subjected to control (100% field capacity) and drought stress (75% and 50% field capacities).
A significant (P ≤ 0.001) reduction in shoot and root lengths of cv. FD1 was observed at 50% drought level. While root length of cv. FD3 remained unchanged under both water regimes. Foliar-applied thiamin was effective (P ≤ 0.001) in improving the lengths (shoot and root) of both cauliflower cultivars as represented in Table 2. Of both cauliflower cultivars, cv. FD3 was lower while cv. FD1 higher in these attributes under water stress conditions (Fig 1).
Table 1.
Mean square values for growth and leaf biochemical characteristics of cauliflower (Brassica oleracea L.) plants treated with thiamin subjected to water deficit stress.
Table 2.
Mean square values (post-hoc analysis) of different growth and biochemical attributes of cauliflower plants treated with thiamin under water deficit stress.
Fig 2.
Leaf chlorophyll a, b, a/b, total chlorophyll, proline and Glycinebetaine (GB) contents of two cultivars of cauliflower (Brassica oleracea L.) plants foliarly treated with thiamin (50 and 100 mM) subjected to control (100% field capacity) and drought stress (75% and 50% field capacities).
A significant increase in leaf proline and GB contents in both cauliflower cultivars was observed particularly at 75% drought stress conditions. Exogenously applied thiamin (50 mM) had a positive effect in enhancing the accumulation of proline in both cauliflower cultivars under water-deficit regimes. Post-hoc analysis showed that cv. FD3 was better in GB accumulation due to exogenously applied thiamin under water-stressed conditions (Fig 2; Table 2).
Fig 3.
Leaf hydrogen peroxide, MDA, ascorbic acid, total phenolics, leaf total soluble, activities of peroxidase, superoxide dismutase and catalase enzymes of two cultivars of cauliflower (Brassica oleracea L.) plants foliarly treated with thiamin (50 and 100 mM) subjected to control (100% field capacity) and drought stress (75% and 50% field capacities).
Accumulation of ascorbic acid (AsA) increased significantly (P ≤ 0.001; 0.01) particularly at 50% F.C. of both cauliflower cultivars. However, foliar applied thiamin (100 mM; P ≤ 0.001) increased AsA contents in both cauliflower cultivars under varying water regimes. A marked difference was noted in both cultivars in terms of AsA contents, and cv. FD1 was significantly better that the other cultivar in AsA contents at varying thiamin and water stress levels (Fig 3).
Fig 4.
Ascorbic acid, total phenolics, proline, GB, hydrogen peroxide, MDA and total soluble proteins in the inflorescence of two cultivars of cauliflower (Brassica oleracea L.) plants foliarly treated with thiamin (50 and 100 mM) subjected to control (100% field capacity) and drought stress (75% and 50% field capacities).
A significant increase in inflorescence proline and GB contents was observed under water-deficit conditions (Fig 4). Exogenous application of thiamin increased (P ≤ 0.001) the contents of GB and proline in both cauliflower cultivars under varying water regimes. A maximum increase in GB and proline contents was recorded in cauliflower plants at 50% F.C.
Fig 5.
Activities of Superoxide Dismutase (SOD), Catalase (CAT) and Peroxidase (POD) enzymes in the inflorescence of two cultivars of cauliflower (Brassica oleracea L.) plants foliarly treated with thiamin (50 and 100 mM) subjected to control (100% field capacity) and drought stress (75% and 50% field capacities).